Method of and apparatus for the generation of pressure inside an enclosed cavity



June 9, 1964 c. BALLHAUSEN 3,135,995 METHOD OF AND APPARATUS FOR THEGENERATION 0F PRESSURE INSIDE AN ENCLOSED CAVITY Filed March 1, 1961 2Sheets-Sheet 1 FIGJ F 4 CARL BALLHAUSEN BYZMMQI @MZfiVW ATTQRNEW SEN THEGENERATION ENCLOSED CAVITY June 9, 1964 Q BALLH METHOD OF AND APPARATUSPRESSURE INSIDE AN Filed March 1, 1961 lNVENlOR All FIG.8

ATTORNEYS United States Patent 3,135,995 7 METHOD OF AND APPARATUS FORTHE GEN- ERATION 0F PRESSURE INSIDE AN ENCLOSED CAVITY Carl Ballhausen,19 Neusserstrasse, Krefeld, Germany Filed Mar. 1, 1961, Ser. No. 92,624I Claims priority, application Germany Mar. 2, 1960 9 Claims. (Cl.18-16) The present invention relates to a method of and a device forgenerating omnidirectional high pressures i.e., pressures from allsides, on a substance in an enclosed cavity. The present inventionenvisages more especially the generation of pressures in theneighbourhood of 400 kg./sq. mm. and more. Such high pressures arerequired for instance for the conversion of certain thermodynamicallystable modifications of substances into thermodynamically unstablemodifications. The principal interest in this connection centres uponthe production of diamonds by submitting graphite to a pressure andtemperature treatment.

According to my copending application filed March 3, 1960, Serial No.15,383, now Patent No. 3,084,388, one method is proposed which consistsin compressing within adie a cartridge made of a plastically deformablematerial, one end of which cartridge initially projects from I the die.The internal capacity (cavity) of the cartridge is thus reduced and aconsiderable omnidirectional in crease in pressure is thus generated onthe substance inside the cavity. This may be effected whilst thesubstance is heated, e.g., electrically, as indicated in my aforesaidapplication. According to the saidapplication, the pressure is appliedin the direction to compress-the plastically deformable cartridgeaxially. Under this pressure the material of the cartridge yieldsinwards in a direction normal to the line of action ofthe appliedforce,causing a reduction in the internal capacity of the cartridge which atthe same time presses against the walls'of the die surrounding thecartridge and causes a certain amount of deformation also of the wallsof the die. By appropriate construction of the die and by suitablyselecting the material of the die this deformation can be kept withinthe load-carrying capacityof the material of the die. A

It has now been recognized, in accordance with this invention that afurther considerable increase in pres sure inside the plasticallydeformable cartridge can be achieved by applying acompressive force tothe die in addition to the application of the compressive force to thecartridge and codirectionally therewith. This can be done by generatingthe compressive force employed for deforming the cartridge and thecodirectional compressive force which acts on the die by means of thesame ram or pair of associated rams. In such a case the procedureconsists in allowing a ram which has a greater diameter than theplastically deformable cartridge first to deform the cartridge and thento act on .the die. Nevertheless, the compressive force applied to thecartridge may be applied by one ram and the compressive force applied tothe die by a separate ram. For instance two concentrically telescopedrams may be used, the two forces being applied simultaneously orconsecutively in predetermined sequence.

It is therefore the principal object of this invention to provide animproved method and apparatus for generating high all-around pressure toa substance by deformation of a deformable metallic cartridge containingthe substance by compressing not only the cartridge fully into a diecavity with ram means but also to compress the die in the same directionas the cartridge, at least in the region surrounding the die cavity andwithout requiring the ram means to enter the cavity.

3,135,995 Patented June 9, 1964.

Other objects and advantages of this invention will become apparent toone of ordinary skill in the art after reading the appended claims, andthe following detailed description of various embodiments of theinvention, in conjunction with the attached drawings, wherein:

FIGURE 1 is a sectional elevation of one embodiment; and

FIGURES 2, 3, 4, 5, 6, 7 and 8 are similar views each showing a furtherdifferent embodiment.

The compressive force acting on the die as above mentioned, may beapplied either directly to the die or at least to the parts of the diewhich directly surround the plastically deformable cartridge, or thesaid force may be transmitted through a layer of plastically deformablematerial which is more or less hardenable under stress and which isinterposed between parts of the die and the ram. I

I For concentrating the pressure generated by the. deformation of thewalls of the die to the immediate surroundings of the cartridge and inthe direction of the axis thereof it is proposed to form one or both ofthe opposed faces of the die in such a way that their shape is at leastapproximately spheroidal or paraboloidal. It is not essential that thefaces of the die which are thus shaped should define the said surfacesin the form of continuous surfaces in the mathematical sense. Thesurfaces may in fact be discontinuous that is to say stepped orsimilarly formed. Moreover, instead of a spheroidal or paraboloidalconformation of the die faces, it has also been found advantageous ifone or both faces of the die slope towards the outer periphery anddefine a cone-shaped configuration. Again the surface .may becontinuous, or discontinuous, i.e. stepped.

As has been mentioned, the compressive force applied to the die may beeither directly applied or transmitted thereto through an interposedplastically deformable more or less stress hardenable material placedbetween die and ram. The inter-position of a plastically deformablematerial of this kind causes the pressure to be transmittedsimultaneously to the whole of the face of the die when the latter iscambered or curved. However, in coni v formity with the relativedeformation ofthe interposed material the specific pressure will thendecrease towards the outside. Moreover, under the effect of the pressurethe interposed material begins to flow radially outwards towards theedge of the die. The friction which is thus engendered tends to expandthe die radially outwards. In, order to. prevent this effect it isfurther proposed to provide an interposed layer, not in the formof adisc ring, but in the form of concentric rings or in the form of aspiral. In the course of the deformation of an intermediate layer ofthis kind, the interposed material will flow both towards the inside ofthe die as well as towards the edge of the die, and consequently theresultant frictional forces will act in contrary directions and thuscancel each other out.

For improving the adhesion of the'intermediate layer, especially if thisis in the form of a spirally coiled wire, it has been found advisableslightly to roughen the faces of the die. Moreover the face of the rammay be treated in a similar way.

Especially when use is made of an intermediate layer in the form of adouble spiral or rings the gaps between neighbouring convolutions of thecoiled wire or between the rings may be used to provide a spiral path ormedium for cooling the device during the process of pressing.

, Cooling may be provided, for instance, by conducting 3 ing drawingswhich schematically represent devices the kind herein described.

FIG. 1 shows the upper part 1 of a compression die which, as indicatedin my aforesaid application, consists of rings of material of differentstrengths and, if desired, also of different compositions. The drawingshows that the rings are slightly coned. This conicity is required topermit the rings to be pressed together. If it is desired to shrink themtogether cylindrical rings may be used. The plastically deformablecartridge, of the type for example referred to in FIGURES 3-5 of myaforesaid application, is indicated at 2 and, in its interior, providesthe compression cavity. At 3 this plastically deformable cartridgeprojects slightly beyond the upper end face of the die 1. 4 representsthe ram which in the drawing applies the pressure required for theplastic deformation of the cartridge 2 as well as the compressive forcewhich acts on the die in the direction indicated by arrows 5. As fullydescribed in my aforesaid Patent 3,084,388, the projecting end 3 of thecartridge is forced by relative movement of the die and ram towards eachother so as to be compressed within the cavity whereby the upper surfaceof the cartridge lies substantially solely within the die due to thecompression elfected by ram 4. The ram 4 is'likewise surrounded by ringswhich contain the ram and increase its resistance in the directionnormal to the pressing direction.

It will be seen at 6 that the end face of the die has a continuousparaboloidal (or possibly spheroidal) shape. In the modification, FIGURE2, the shape of the end face of the die at 7 is similar but thecurvature extends not across the entire width of the ring area of thesaid face but across about only half that width. At 8 it will be seenthat the rings which surround the ram may likewise be shaped to define asimilar end face rings area or surface. This, on the one hand, increasesthe lateral load-supporting capacity of the ram and, on the other,provides more clearance for the interposition of the afore-mentionedplastically deformable intermediate layers between ram and die.

Similarly to the die in my above mentioned patent, the central elementwhich forms the cavity of the die herein, as well as the other ringswhich surround that central ring, may be made, for instance, of a steelwhich which has been submitted to a previous thermal treatment or whichhas been cold worked in such manner that the rings have increasingstrength progressively to the inside, whereby the outer ring has thelowest mechanical strength and the inner or central ring is thestrongest. Likewise cartridge 2 may be similar to the cartridgedescribed in detail in that prior patent of mine, though any othercartridge may be employed as long as it has at least one end whichprojects from the die as above described.

FIG. 3 is a similar embodiment to that of FIG. 1,

the only difference being that the end face 9 of the die is shown toslope away in the form of a shallow central cone. In the modifiedembodiment, FIG. 4, the end face 10 of the die is radially stepped bythe separate rings.

In the embodiment shown in FIG. an intermediate flat disc ring 11 isinterposed between the upper end face of the die 12 and the opposinglower end face of the ram 13 and its surrounding rings 14. The surfacesof the ring are suitably shaped to conform with the surfaces of the dieand of the ram and its rings.

Instead of providing an interposed layer of plastically deformablestress-hardenable material in the form of a flat disc-shaped ring 11, aseries of co-axial wire rings as indicated at 15, in FIGURE 6, may beinterposed between the opposed faces of the die and ram and the ringsthereof. The wires in this embodiment are of rectangular cross-sectionand of changing dimension as illustrated. The rings, may be of circularcross-section as shown in the embodiment according to 'FIG. 7, the rings16 being of progressively greater diameter in the outward direction.FIG. 8 shows a form in which the rings 17 are of substantiallytriangular cross section. The wires may however be of any suitablecross-sectional contour.

Substances suitable for treatment by the present method and suitablematerials for the compressible cartridge are described in the aforesaidapplication and other features described therein are applicable to thepresent method. The plastically deformable rings herein before referredto may be of an austenitic steel with a content of about 17% chromiumand 7% nickel. For obtaining diamond from graphite a suitable rampressure is 100,000 kg./sq. mm.

What I claim is:

1. A method of generating high all-round pressure to a substance bydeformation of a deformable metallic cartridge containing the saidsubstance, which comprises arranging the said metallic cartridgecontaining the said substance in a cavity in a die with opposed endfaces '50 that an end portion of the cartridge projects beyond at leastone said end face of the die, compressing the cartridge by means of anopposing member while maintaining the said member outside the saidcavity to compress said cartridge end portion substantially solelywithin the die, and, at least by the time when the said cartridge endportion has been brought within the said cavity, causing the saidopposing member to apply compressive force to the die itselfco-directionally with the direction in which it applies compressiveforce to the cartridge to deform the die around the said cavity toincrease the load supporting capacity of the die.

2. A method of generating high all-round pressure to a substance bydeformation of a deformable metallic cartridge containing the saidsubstance, which comprises arranging the said metallic cartridgecontaining the said substance in a cavity of a die having a memberforming a die cavity and surrounded by concentric hard metallic rings,so that the end portion of the cartridge projects beyond the end face ofthe said member forming the said cavity, compressing the cartridge bymeans of an opposing member comprised of a central plunger andsurrounding reinforcing rings while maintaining the said plunger outsidethe said cavity so that said cartridge end portion lies solely withinthe said cavity, and, at least when the said cartridge end portion hasbeen brought within the said cavity, causing the plunger and rings ofthe said opposing member to apply compressive force to the cavityforming member and said rings of the die co-directionally with thedirection in which the plunger applies its compressive force to thecartridge.

3. The method according to claim 2 in which compressive force is appliedprogressively to the outer regions of the die and in the same directionas the direction of compression of the cartridge after initiallycompressively stressing the die in the region of the said cavity-formingmember and immediately surrounding the die cavity.

4. The method according to claim 2 including transmitting the saidco-directional compressive force to the said cavity forming member andsaid rings of the die through the medium of plastically deformablestresshardenable material interposed between the corresponding end faceof the die and said opposing member.

5. Apparatus for generating high all-round pressure in the interior of ametallic cartridge containing a substance that is to be compressed,comprising a die comprised of a central component providing a cavity forthe said cartridge and surrounding reinforcing rings, said die beingadapted to receive the cartridge with an end portion projecting from anend face of the said central component, at least one opposed meanscomprised of a central plunger and surrounding reinforcing rings forcausing the plunger, without entering the said cavity, to applycompressive force to the cartridge to compress the cartridge whollywithin the cavity and means to apply compressive forces to the centralcomponent and rings of the die in the same 5. direction as the plungerapplies its compressive force to the cartridge to deform the die aroundthe said cavity and increase the load supporting capacity of the die.

6. Apparatus for generating high all-round pressure in the interior of ametallic cartridge containing a substance that is to be compressed,comprising a die comprised of a central component providing a cavity forthe said cartridge and surrounding reinforcing rings, said die beingadapted to receive the cartridge with an end portion projecting from anend face of the said central component, means including at least oneopposed means comprised of a central plunger and surrounding reinforcingrings for causing the plunger, without entering the said cavity, toapply compressive force to the cartridge to compress the cartridgewholly within the cavity and to apply compressive forces to the centralcomponent and rings of the die in the same direction as the plungerapplies its compressive force to the cartridge to deform the die aroundthe said cavity and increase the load supporting capacity of the die, inwhich said central component of the die has its end face nearer to theopposed face of the plunger of the opposing member than thecorresponding end faces of the rings of the die are to the opposed endfaces of the rings of the opposing member so that the opposing membercan concentrate pressure of compression in the central component of thedie and then apply pressure to the successive rings of the diesurrounding the said central component.

7. Apparatus for generating high all-round pressure in the interior of ametallic cartridge containing a substance that is to be compressed,comprising a die comprised of a central component providing a cavity forthe said cartridge and surrounding reinforcing rings, said die beingadapted to receive the cartridge with an end portion projecting from anend'face of the said central component, means including at least oneopposed means comprised of a central plunger and surrounding reinforcingrings for causing the plunger, Without entering the said cavity, toapply compressive force to the cartridge to compress the cartridgewholly within the cavity and to apply compressive forces to the centralcomponent and rings of the die in the same direction as the plungerapplies its compressive force to the cartridge to deform the die aroundthe said cavity and increase the load supporting capacity of the die, inwhich the die is shaped so that its end face opposing the opposingmember and constituted by the rings of the die slopes towards theperiphery of the die progressively to increase the distance parallel tothe axis of the die of the said end face from the opposing face of thesaid opposing member.

8. Apparatus for generating high all-round pressure in the interior of ametallic cartridge containing a substance that is to be compressed,comprising a die comprised of a apply compressive force to the cartridgeto compress the cartridge wholly within the cavity and to applycompressive forces to the central component and rings of the die in thesame direction as the plunger applies its compressive force to thecartridge to deform the die around the said cavity and increase the loadsupporting capacity of the die, in which the die is shaped so that itsend face opposing the opposing member and constituted by the rings ofthe die is stepped radially outwards to the periphery of the die so asin steps to increase the distance parallel to the axis of the die of thesaid end face from the opposing face of the said opposing member.

9. Apparatus for generating high all-round pressure in the interior of ametallic cartridge containing a substance that is to be compressed,comprising a die comprised of a central component providing a cavity forthe said cartridge and surrounding reinforcing rings, said die beingadapted to receive the cartridge with an end portion projecting from anend face of the said central component, means including at least oneopposed means comprised of a central plunger and surrounding reinforcingrings for causing the plunger, without entering the said cavity, toapply compressive force to the cartridge to compress the cartridgewholly within the cavity and to apply compressive forces to the centralcomponent and rings of the die in the same direction as the plungerapplies its compressive force to the cartridge to deform the die aroundthe said cavity and increase the load supporting capacity of the die, incombination with rings of plastically deformable material co-operativewith said rings of the said die, said plastically deformable rings beingof different height in relation to the axial direction of the die andbeing engageable by the said opposing member for compression thereby tobuild-up in the die compressive-stress regions progressively outwards tothe peripheral region of the die.

References Cited in the file of this patent UNITED STATES PATENTS2,941,241 Strong June 21, 1960 2,941,245 Cheney June 21, 1960 2,941,248Hall June 21, 1960 2,995,776 Giardini et al. Aug. 15, 1961 3,061,877Custers et al. Nov. 6, 1962 3,084,388 Ballhausen Apr. 9, 1963

5. APPARATUS FOR GENERATING HIGH ALL-ROUND PRESSURE IN THE INTERIOR OF A METALLIC CARTRIDGE CONTAINING A SUBSTANCE THAT IS TO BE COMPRESSED, COMPRISING A DIE COMPRISED OF A CENTRAL COMPONENT PROVIDING A CAVITY FOR THE SAID CARTRIDGE AND SURROUNDING REINFORCING RINGS, SAID DIE BEING ADAPTED TO RECEIVE THE CARTRIDGE WITH AN END PORTION PROJECTING FROM AN END FACE OF THE SAID CENTRAL COMPONENT, AT LEAST ONE OPPOSED MEANS COMPRISED OF A CENTRAL PLUNGER AND SURROUNDING REINFORCING RINGS FOR CAUSING THE PLUNGER, WITHOUT ENTERING THE SAID CAVITY, TO APPLY COMPRESSIVE FORCE TO THE CARTRIDGE TO COMPRESS THE CARTRIDGE WHOLLY WITHIN THE CAVITY AND MEANS TO APPLY COMPRESSIVE FORCES TO THE CENTRAL COMPONENT AND RINGS OF THE DIE IN THE SAME DIRECTION AS THE PLUNGER APPLIES ITS COMPRESSIVE FORCE TO THE CARTRIDGE TO DEFORM THE DIE AROUND THE SAID CAVITY AND INCREASE THE LOAD SUPPORTING CAPACITY OF THE DIE. 